The machines for the manufacture of glass articles such as the ones heretofore mentioned have been well known for a long time, and they consist, basically, of a gyratory table provided with a plurality of mold supporters--carrying respective molds for the manufacture of glass articles--which gyrate simultaneously with the table, passing through a number of stations, among which are stations for charging, stations for pressing and cooling of articles, extracting stations, and stations for the cooling of molds, so as to achieve--in a complete cycle--the production of a finished article already cooled to be taken out of the machine and passed onto a belt conveyor, as well as the further total cooling of the mold, in order to renew the cycle with the charging of another glass gob, thus continuing the manufacture of articles.
It is well known, however, that one of the main problems of this type of machines is that the process is controlled by a mechanical timing drum, which comprise, a rotary drum having a plurality of circumferential grooves on its surface, within which a corresponding plurality of cams are arranged in position suitable to timely actuate cam followers associated with cam operated valves to sequentially and timingly operate all the mechanism of the machine.
The prior art timing drum is generally rotatable driven in synchronism with the gob feeding means and with the pressing machine.
As the timing drum associated with the pressing machine rotates, the several fluid operates forming means, including all the mechanisms are mechanically actuated in the required sequence as determined by the control of the valves which are opened and closed by the cams.
While the cam position may be more or less accurately adjusted with the drum stationary at the start of a run, it is generally necessary to adjust the position of said cams when the machine is operating in order to secure an efficient function of the mechanism of the pressing machine. It is generally undesirable to stop the machine during a run to permit adjustment of a cam, since, as is well known in the art, the pressing machine desirably achieve and maintain a thermal balance upon continued operation, and therefore sometimes it becomes necessary to carry out adjustment of certain cams when the machine is working and thus the drum is rotating.
In an effort to avoid the aforementioned problems, the present invention is referred to a method and an apparatus for controlling a pressing machine for the manufacture of glass articles and more specifically to a control system for controlling and protecting the movements of the mechanisms, the indexing of the table and the monitoring of the process variables needed for obtaining good quality press articles with high production rates.